While many archaeologists in easternNorth America (ENA) no longer as-sume that the adoption of maize (Zea

mays ssp. mays) in any given area necessarily trig-gered significant changes in subsistence, settle-ment, or various aspects of social complexity, theadoption and the evolution of maize-based agri-culture remain important topics of research (e.g.,Hart, ed. 2008; Staller et al. 2006). For example,the chronology of the introduction of maize to dif-ferent regions, why maize persisted in cultures forcenturies before it became a dietary staple, andthe dynamics that engendered the shift to intensivemaize agriculture are still hotly debated topics.Important to addressing these and various relatedissues are direct lines of evidence for maize use.

Direct evidence prior to ca. A.D. 900 has beenlacking in many areas of ENA. Whether this lackof evidence accurately reflects an absence ofmaize use remains an open question. A relianceon carbonized macrobotanical remains alone toassess initial maize use is highly problematicgiven various taphonomic and sampling issues(Hart 1999, 2008; Parker 1996). As a result ar-chaeologists have relied increasingly on microb-otanical remains (e.g., lipids, phytoliths, starches)and chemistry (e.g., carbon isotopes) from charredcooking residues encrusted on pottery to buildregional chronologies of maize use (e.g., Boydand Surette 2010; Messner et al. 2008; Mortonand Schwarcz 2004), as well as isotopic analysesof human bone for direct evidence for maize con-

THE POTENTIAL OF BULK �13C ON ENCRUSTED COOKINGRESIDUES AS INDEPENDENT EVIDENCEFOR REGIONAL MAIZE HISTORIES

John P. Hart, William A. Lovis, Robert J. Jeske, and John D. Richards

The histories of maize utilization in eastern North America have been substantially revised recently, primarily because ofthe analysis of charred cooking residues encrusted on pottery. A multifaceted research strategy of bulk �13C assays coupledwith accelerator mass spectrometry radiocarbon data and microbotanical evidence can yield coherent regional maize usehistories. Bulk �13C assay interpretation complications include (1) variations among vessels by site, (2) a potential for falsenegatives, and (3) a wide range of variation potentially present for any given time period. Regional histories using thisapproach can be quite variable without appropriate use of multiple lines of evidence.

Las historias de la utilización del maíz en el este de Norteamérica han sido revisadas considerablemente en años recientesdebido principalmente a los análisis de residuos carbonizados que se encuentran incrustados al interior de tiestos de cerámica.Una estrategia multifacética de investigación de los valores del cúmulo de �13C junto con datos de radiocarbono AMS, asícomo evidencia microbotánica, puede proporcionar historias coherentes del uso del maíz en la región. La interpretación dela prueba del cúmulo de �13C se complica debido a 1) variaciones entre vasijas por sitio, 2) el potencial de negativos falsos,y 3) un amplio rango de variabilidad potencialmente presente durante cualquier periodo de tiempo. Historias regionales queutilicen este método pueden resultar bastante variables sin el uso apropiado de múltiples líneas de evidencia.

John P. Hart � Research and Collections Division, New York State Museum, 3140 Cultural Education Center, Albany, NY12230 (jph_nysm@mail.nysed.gov)William A. Lovis � Department of Anthropology and Michigan State University Museum, 355 Baker Hall, Michigan StateUniversity, East Lansing, MI 48824 (lovis@msu.edu)Robert J. Jeske � Department of Anthropology, University of Wisconsin–Milwaukee, 290 Sabin Hall, P.O. Box 413, 3413N. Downer Ave., Milwaukee, WI 53201 (jeske@uwm.edu)John D. Richards � Department of Anthropology, University of Wisconsin–Milwaukee, 290 Sabin Hall, P.O. Box 413,3413 N. Downer Ave., Milwaukee, WI 53201 (jdr@uwm.edu)

American Antiquity 77(2), 2012, pp. 315–325Copyright ©2012 by the Society for American Archaeology

315

AQ77(2)8-Hart_Layout 1 4/10/12 3:30 PM Page 315

316 american antiquity [Vol. 77, no. 2, 2012]

sumption (e.g., Harrison and Katzenberg 2003;Rose 2008). Thus, it is evident that use of multi-ple, independent lines of evidence— and under-standing their relationships to each other— increases confidence in both specific and generalexplanations for maize adoption and use. In thepresent article we explore one such potential lineof evidence, bulk �13C on directly acceleratormass spectrometry (AMS)–dated, charred cook-ing residues encrusted on pottery sherd interiors(hereafter residues). We restrict our attention hereto bulk �13C values because they are routinelysupplied by AMS labs and, as a result, are readilyaccessible as potential sources of data on maizeuse histories. We accept that systematic regionalresearch into diet composition might include otherproxy measures, such as 15N isotopes, as part ofthe protocol. We urge researchers to request thesemeasurements routinely when they obtain AMSdates from residues.

While initially seen as useful in determiningwhether maize, a C4-pathway plant, had beencooked in a pot (Hastorf and DeNiro 1985; Mortonand Schwarcz 2004), the relationship betweenmaize use and bulk �13C became suspect aftermaize phytolith assemblages were extracted fromdirectly AMS-dated residues in central New Yorkthat had depleted bulk �13C values (Hart et al.2003). Subsequent controlled experiments demon-strated that interpreting bulk �13C values fromresidues is problematic and cannot serve as an in-dependent source of evidence for maize use in agiven pot or assemblage of pots from specific siteoccupations (Hart et al. 2007b; Hart et al. 2009).

These experiments did not, however, rule outthe possibility that bulk �13C values from residuesmay be used for other analytical purposes (e.g.,Seinfeld et al. 2009). Here we demonstrate thatlarge series of chronologically controlled bulk�13C values may provide supporting evidence forregional maize use histories independent of athreshold value for maize use identification. Wedo this by examining temporal trends in bulk �13Cvalues on residues from central New York, wherephytolith evidence indicates a long history ofmaize use before the evolution of intensive agri-culture. Results indicate significant trends for theenrichment of bulk �13C values and, therefore,increased contribution of maize C to residue for-mation. We compare these results to bulk �13C

value data sets from Michigan and southeasternWisconsin/northeastern Illinois, where data wereassembled for different purposes: in the former,primarily the timing of the early introduction ofceramics and in the latter, ceramic type chronolo-gies. Our results indicate that chronological trendsin bulk �13C can provide complementary evidencefor maize use histories. However, disparate and/ordeficient data may prevent systematic interre-gional comparisons. We suggest that if archaeol-ogists routinely adopt a few analytical techniques(e.g., microbotanical analyses) along with thewell-accepted AMS dating of residues and bulk�13C, such systematic comparisons will be possi-ble in the near future.

Bulk �13C and Maize Detection in Charred,Encrusted Residues

The use of bulk �13C from residues as a proxysignature by which to identify maize use was firstsuggested by Hastorf and DeNiro (1985). An un-derlying assumption was that maize was the onlyC4 resource cooked in the pot. The presence of aC4 resource in a mixture with C3 resources wouldresult in enriched bulk �13C values on residues.Enriched bulk �13C values could then be used toassess the use of maize in pots from regions, suchas ENA, where maize is the most likely C4 re-source to have been exploited for human food(Lovis 1990). Two decades later, Morton andSchwarcz (2004) used this reasoning to determinewhether or not maize was cooked in pots fromsouthern Ontario. They assumed a linear rela-tionship between the proportion of maize cookedin a pot relative to C3 resources and bulk �

13Cvalues on residues. They also suggested –24‰as a threshold for bulk �13C values to identify thepresence of maize. In their analysis of temporaltrends, Morton and Schwarcz (2004:508) foundonly a weak trend for enriched bulk �13C values.It was only after A.D. 800 that mean �13C valuesfor sites regularly exceeded their threshold formaize identification, an age consistent with maizehistories based on dated carbonized macrobotan-ical remains.

The presence of maize phytoliths in residueswith depleted bulk �13C values from central NewYork raised questions as to the validity of a thresh-old value for maize (Hart et al. 2003). Subse-

AQ77(2)8-Hart_Layout 1 4/10/12 3:30 PM Page 316

quently, combined data from three independentseries of experimental residues using mixes ofmaize and C3 resources showed that the relation-ship between maize proportions and bulk �13Cvalues is nonlinear and varies based on the C3 re-source (Hart et al. 2007b). Experimental residuescreated with up to 80 percent maize produced de-pleted bulk �13C values that were below the Mor-ton and Schwarcz threshold adjusted for indus-trial-era atmospheric carbon. Mathematicalmodeling indicated that it was the amount of Ccontributed to residue formation by maize andeach C3 resource that determined bulk �

13C values;C content varies among food resources. Subse-quent research determined that it is the mobiliza-tion of C into suspension and solution over timethat is the most critical factor (Hart et al. 2009).Increased cooking time in many of the experi-ments resulted in more depleted bulk �13C valuesfor different resource mixes. Significantly, theform of maize being cooked (e.g., green kernels,hominy, meal) determined the rate of C mobiliza-tion relative to mobilization in C3 resources. Theseresults indicate that it is not possible to determinethe proportion of maize that had been cooked in apot through either linear or nonlinear modeling.It is also not possible to identify an absolute thresh-old value for the identification of maize use.Rather, the interpretation of any given bulk �13Cvalue relies on knowing a priori what was cookedin that pot (Hart et al. 2009:2210–2211).

Whether bulk �13C values on residues can beused to track maize use histories, however, re-mains an open question. Morton and Schwarcz(2004:508) found a weak correlation (r = .360)between chronology and residue �13C values insouthern Ontario. Several problems limit the util-ity of their analyses. First, there is a gap in Mortonand Schwarcz’s (2004:Figure 3) sample betweenapproximately A.D. 150 and A.D. 750, whichlikely influences their results. Limiting the daterange from A.D. 750 and younger results in ahigher correlation (r = .476). Additionally, noneof the residues in their study are dated directly.Finally, Morton and Schwarcz do not provide val-ues for specific residues but, rather, report meansand standard deviations by site. Despite all of thevariables affecting bulk �13C values, their corre-lations do suggest the possibility of a generaltemporal trend for increased maize C contribu-

tions to residue formation independent of a thresh-old value for maize use. Their research suggeststhat large series of chronologically controlledbulk �13C values may provide useful evidenceconcerning regional maize use histories, as sug-gested as one potential outcome of previous ex-perimental results (Hart et al. 2009).

Bulk �13C Values in Central New York State

As part of a long-term project to develop historiesfor maize and other agricultural crops in centralNew York, a series of residues have been subjectedto direct AMS dating (Table 1). Maize phytolithassemblages have been extracted from 18 of thesesame residues, which establish a long history formaize use, beginning by at least ca. cal 300 B.C.(Table 1; Hart and Matsen 2009; Hart et al. 2007a).Bulk �13C values were also obtained for theseresidues as part of the AMS dating process.

Bulk �13C values are plotted against calibratedmedian probability dates in Figure 1 for 57residues with locally weighted scatter plotsmoothing, distance-weighted least squares, andlinear smoothing. The plot begins at 300 B.C.,when there is phytolith evidence for maize use.Only eight of the residues, all postdating A.D.1200, produce bulk �13C values above the –24‰threshold suggested by Morton and Schwarcz(2004) for the presence of maize. However, eachsmoothing technique indicates a general trend formore enriched values through time. The nonpara-metric smoothing techniques evince steeperslopes after ca. cal A.D. 400–500, suggesting amore rapid increase in maize C contribution toresidue formation than earlier. The dip in the dis-tance-weighted least squares curve beginning atcal A.D. 1400 can be accounted for by two de-pleted values at cal A.D. 1560. The small numberof samples at this time prevents us from assigningany significance to this trend.

There is a relatively strong correlation betweencalibrated median probability dates and �13C val-ues (r = .675, p < .05). This correlation is strongerwhen only the 18 cases containing maize phy-toliths are used (r = .793, p < .05).1 The respectiveR2 values of .456 and .628 suggest that relativelyhigh percentages of the variation in �13C valuesare explained by time. Given that there are com-plex relationships between C mobilization of

rePOrtS 317

AQ77(2)8-Hart_Layout 1 4/10/12 3:30 PM Page 317

318 american antiquity [Vol. 77, no. 2, 2012]

Table 1. Data on Encrusted, Charred Cooking Residues from Central New York State.

MaizeSite NYSM # Phytoliths?a ISGS # �13C 14C B.P. Cal 2� (median probability)

Vinette 40031-2 Yes A0500 –28.1 2270 ± 35 399 (307) 208 B.C.Felix 40701-21 N/a A0505 –30.0 2205 ± 30 376 (283) 197 B.C.Kipp Island 42698-30 N/a A0747 –28.1 2055 ± 35 170 B.C. (72 B.C.) A.D. 20Kipp Island 42712A-9 N/a A0758 –24.6 1910 ± 30 21 B.C. (A.D. 94) 210Fortin 2 46238-26 Yes A0410 –29.0 1995 ± 35 90 B.C. (A.D. 5) 80Vinette 40046 Yes A0455 –29.8 1990 ± 40 93 B.C. (A.D. 9) 119Vinette 40135 Yes A0452 –29.3 1940 ± 35 37 B.C. (A.D. 61) 130Cottage 44477-29 N/a A0760 –27.5 1810 ± 30 A.D. 127 (198) 322Cottage 44469-55 N/a A0762 –25.5 1805 ± 30 A.D. 129 (206) 322Wickham 40291-3 No A0454 –30.4 1695 ± 35 A.D. 255 (349) 418Wickham 40170 No A0194 –29.0 1648 ± 47 A.D. 259 (403) 537Wickham 40290-5 No A0453 –28.0 1635 ± 35 A.D. 339 (419) 536Simmons 40518-1 No A0542 –28.7 1620 ± 35 A.D. 349 (448) 540Westheimer 44533-67 Yes A0498 –25.9 1600 ± 35 A.D. 393 (475) 544Wickham 40445-38 N/a A0745 –29.1 1575 ± 30 A.D. 418 (485) 551Felix 40797-18 N/a A0648 –26.9 1555 ± 30 A.D. 425 (491) 570Fortin 2 46232-80 No A0407 –29.0 1505 ± 35 A.D. 435 (565) 639Fortin 2 46238-16 Yes A0406 –29.0 1525 ± 35 A.D. 432 (542) 605Felix 40788-3 Yes A0497 –27.2 1575 ± 35 A.D. 413 (485) 565Felix 40690-9 Yes A0503 –27.9 1525 ± 40 A.D. 428 (540) 612Felix 40647-1 No A0504 –27.4 1520 ± 35 A.D. 432 (542) 610Felix 40727-19 Yes A0499 –27.3 1430 ± 40 A.D. 559 (620) 662Felix 40652-18 No A0502 –26.7 1405 ± 40 A.D. 570 (634) 662Felix 40677-9 Yes A0506 –26.3 1315 ± 50 A.D. 637 (708) 860Wickham 40525-1 Yes A0190 –28.1 1425 ± 45 A.D. 552 (621) 667Wickham 40194 N/a A0195 –29.7 1450 ± 43 A.D. 542 (607) 658Simmons 40518-2 Yes A0501 –29.7 1390 ± 35 A.D. 594 (645) 683Kipp Island 42719-35 N/a A0761 –25.5 1545 ± 25 A.D. 430 (499) 573Kipp Island 41119-5 Yes A0225 –26.4 1470 ± 43 A.D. 443 (592) 656Kipp Island 41119-2 N/a A0226 –26.5 1461 ± 43 A.D. 469 (599) 659Kipp Island 41119-8 Yes A0227 –27.0 1428 ± 41 A.D. 559 (621) 663Kipp Island 42719-21 N/a A0757 –25.6 1315 ± 30 A.D. 654 (693) 771Kipp Island 42729-5 N/a A0228 –26.1 1260 ± 39 A.D. 668 (743) 869Wickham 40525-8 No A0191 –25.8 1228 ± 42 A.D. 681 (792) 889Hunters Home 48580-110 Yes A0192 –26.7 1231 ± 44 A.D. 678 (787) 889Hunters Home 48580-115 N/a A0193 –27.2 1286 ± 40 A.D. 655 (725) 859Hunters Home 41356-6 N/a A0197 –27.5 1247 ± 48 A.D. 655 (766) 884Hunters Home 48584-1 No A0198 –27.8 1211 ± 46 A.D. 682 (812) 944Levanna 36311-1 N/a A0742 –25.6 1175 ± 30 A.D. 774 (849) 964Hunters Home 41797 N/a A0196 –24.9 1138 ± 40 A.D. 779 (909) 988Levanna 36319 N/a A0754 –26.1 1115 ± 35 A.D. 784 (934) 1016Wickham 40509-27 N/a A0751 –24.1 1115 ± 30 A.D. 870 (935) 1013Street 48217-10 Yes A0229 –26.1 1043 ± 40 A.D. 892 (999) 1117Felix 40697-23 N/a A0646 –25.6 995 ± 35 A.D. 983 (1036) 1154Lakeside 33061-A N/a A0749 –23.0 845 ± 25 A.D. 1158 (1199) 1258Haner n/a N/a A0235 –18.1 781 ± 42 A.D. 1176 (1243) 1255Lakeside 33161-A N/a A0750 –23.3 735 ± 30 A.D. 1224 (1272) 1293Kelso 41101-81 N/a A0759 –24.3 520 ± 30 A.D. 1324 (1416) 1443Pompey 32729 N/a A0748 –22.4 515 ± 35 A.D. 1322 (1417) 1446Smith 44728-13 No A0528 –20.7 445 ± 40 A.D. 1408 (1448) 1618Klock 45738-43 Yes A0523 –23.6 480 ± 40 A.D. 1327 (1431) 1475Goff 71210-1 N/a A0744 –22.9 470 ± 30 A.D. 1410 (1435) 1457Goff 71210-2 N/a A0763 –24.1 460 ± 30 A.D. 1413 (1438) 1467Buyea 42906-19 N/a A0756 –25.2 455 ± 30 A.D. 1414 (1440) 1626Garoga 42826-2 Yes A0522 –20.8 425 ± 40 A.D. 1414 (1465) 1626Buyea 42909-32 N/a A0755 –29.1 355 ± 30 A.D. 1454 (1549) 1634Richmond Mills 34635-449 N/a A0743 –25.3 355 ± 30 A.D. 1454 (1549) 1634aSee Hart and Matson 2009; Hart et al. 2007a.

AQ77(2)8-Hart_Layout 1 4/10/12 3:30 PM Page 318

maize vs. C3 resources, and the potential thatmaize did not necessarily contribute to residueformation in all vessels, the results from these 57residues suggest that there was a general gradualincrease in the amount of C originating frommaize over time in residue formation despite thefact that �13C values do not approach that associ-ated with C4 plants. Prior research (Hart et al.2007b; Hart et al. 2009) suggests that �13C valuesare the result of any combination of changes inthe forms of maize being used (e.g., from greenkernels to meal or flour), changes in the C3 re-

sources being cooked with maize (e.g., from wildrice to deer meat), or the differences in propor-tions of these resources, such as a general increasein the proportion of maize being cooked in anygiven resource mix.

The origination of the bulk �13C values usedhere was the result of a research program that wasdesigned specifically to obtain chronological in-formation on pottery and agricultural crop histo-ries. As a result, the sampling was deliberatelychronological from a geographically restricted re-gion and generated independent evidence for

rePOrtS 319

Figure 1. Bulk �13C values on charred, encrusted cooking residues from central New York State plotted against calibratedmedian probabilities of direct accelerator mass spectrometry dates on the same residues, with locally weighted scatterplot smoothing (solid line), distance-weighted least squares (dashed line), and linear smoothing (dotted line). The hori-zontal line represents the –24‰ threshold suggested by Morton and Schwarcz (2004) for the presence of maize in bulk�13C values.

AQ77(2)8-Hart_Layout 1 4/10/12 3:30 PM Page 319

maize use. Before drawing a conclusion that largeseries of bulk �13C values on residues can con-tribute interpretable information on regional maizehistories, it is necessary to examine data sets cre-ated for different purposes. These include regionalcompilations of bulk �13C on AMS-dated residuesfrom independent projects and from single projectslacking the complementary microbotanical evi-dence. To explore the potential of such large setsof bulk �13C values on directly dated residues fur-ther, we analyze data from Michigan and thesouthwestern Lake Michigan region (northeasternIllinois and southwestern Wisconsin).

Interregional Comparisons

A data set from the Saginaw River and GrandRiver basins in Michigan was compiled from var-

ious projects as listed in Table 2. Microbotanicalevidence from residues for maize use in the Sag-inaw River Basin extends from cal 2� 350–40B.C. to cal 2� A.D. 1440–1640 (Raviele 2010).A plot of 32 bulk �13C values by calibrated medianprobability date is provided in Figure 2.2 The ma-jority of dates fall between cal 300 B.C. and A.D.200. These and the rest of the data do not show atrend for increased C contribution from maize;the dip in the center of the nonparametric trendlines is probably the result of sampling error. Thereis a weak, nonsignificant negative correlation be-tween bulk �13C values and dates (r = –.296, p >.05). The gap in assays between cal A.D. 200 and600 and the relatively sparse number of subsequentassays may account for the lack of significanttrends. Whether sampling error alone explains thecurrent lack of trend for enriched �13C values over

320 american antiquity [Vol. 77, no. 2, 2012]

Table 2. Data from Michigan Sites (* notation means �13C values provided independently of publication).

Site Beta# River Basin �13C 14C B.P. Cal. 2� (median prob.) Source

Arthurburg Hill 67203 Grand -17.5 2255±55 403 (289) 193 B.C. Beld 1993a

Prison Farm 113899 Grand -27.2 2140±40 356 (179) 50 B.C. Brashler et al. 2006a

Prison Farm 113897 Grand -27.4 2130±40 354 (170) 46 B.C. Brashler et al. 2006a

Schultz 261459 Saginaw -26.2 2070±40 195 (90 B.C.) A.D. 17 Brashler pers. comm. 2010Prison Farm 113898 Grand -27.7 2060±40 184 (81 B.C.) A.D. 24 Brashler et al. 2006a

Converse 153907 Grand -30.3 2040±40 167 (49 B.C.) A.D. 51 Brashler et al. 2006a

Schultz 261449 Saginaw -26.1 2040±40 167 (49 B.C.) A.D. 51 Raviele 2010Prison Farm 83091 Grand -29.4 2030±40 164 (35 B.C.) A.D. 57 Brashler et al. 2006a

Converse 153908 Grand -28.2 2010±40 154 (11 B.C.) A.D. 74 Brashler et al. 2006a

Schultz 261455 Saginaw -29.8 2000±40 151 (1 B.C. ) A.D. 83 Raviele 2010Schultz 262040 Saginaw -25.8 2000±40 151 (1 B.C. ) A.D. 83 Raviele 2010Schultz 261460 Saginaw -26.9 1990±40 93 B.C. (A.D. 7) 119 Raviele 2010Converse 148361 Grand -26.1 1990±40 93 B.C. (A.D. 7) 119 Brashler et al. 2006a

20SA1276 261450 Saginaw -27.5 1980±40 87 B.C. (A.D. 19) 124 Raviele 201020SA1251 177615 Saginaw -26.4 1960±40 43 B.C. (A.D. 39) 125 Sommer 2003Prison Farm 113894 Grand -27.4 1950±40 40 B.C. (A.D. 49) 128 Brashler et al. 2006a

Paggeot 113892 Grand -27.5 1950±40 40 B.C. (A.D. 49) 128 Brashler pers. comm. 2010Prison Farm 113896 Grand -27.9 1940±40 44 B.C. (A.D. 60) 135 Brashler pers. comm. 2010Converse 148359 Grand -26.0 1910±40 A.D. 5 (95) 216 Brashler et al. 2006a

Converse 153909 Grand -30.0 1850±40 A.D. 71 (165) 249 Brashler et al. 2006a

Fletcher 17752 Saginaw -30.0 1830±40 A.D. 79 (190) 319 Lovis 1990Zemaitis 83092 Grand -28.3 1470±40 A.D. 467 (594) 655 Brashler pers. comm..Casassa 78227 Saginaw -30.8 1440±40 A.D. 553 (607) 658 Branstner and Hambacher 1995a

Hacklander 231468 Grand -28.5 1300±40 A.D. 649 (714) 807 Brashler pers. comm. 2010Zemaitis 83093 Grand -27.6 1260±40 A.D. 668 (744) 869 Brashler pers. comm. 2010Fletcher 17748 Saginaw -29.3 1275±40 A.D. 660 (760) 863 Lovis 1990Fletcher 17749 Saginaw -29.6 1065±40 A.D. 893 (963) 1024 Lovis 1990Fletcher 17750 Saginaw -32.0 875±40 A.D. 1040 (1149) 1252 Lovis 1990Fletcher 17751 Saginaw -30.6 785±40 A.D. 1178 (1224) 1283 Lovis 1990Casassa 78226 Saginaw -23.8 630±40 A.D. 1285 (1347) 1401 Branstner and Hambacher 1995a

Ada Warner 113891 Grand -26.4 480±40 A.D. 1327 (1431) 1475 Brashler pers. comm. 2010Casassa 78225 Saginaw -27.0 440±40 A.D. 1410 (1452) 1619 Branstner and Hambacher 1995a

a�13C values provided independently of publication.

AQ77(2)8-Hart_Layout 1 4/10/12 3:30 PM Page 320

time may potentially be resolved through dataaugmentation and/or through exploration of re-gionally pertinent alternative hypotheses.

In contrast is a series of 49 post-300 B.C.direct AMS dates and bulk �13C values from thesouthwestern Lake Michigan region (Table 3).Most of these assays were obtained as part of asingle project undertaken as part of a Universityof Wisconsin–Milwaukee Research InitiativeGrant to assess pottery type chronologies (Jeskeand Richards 2010). Microbotanical analyses ofthe residues were not part of the project. As shownin Figure 3, there is a trend for �13C enrichmentusing the nonparametric smoothing techniquesuntil ca. cal A.D. 800–900, after which the trendlines are basically flat. There is a positive corre-lation between bulk �13C values and median prob-ability dates (r = .429, p < .05). The R2 value of.184 indicates that little of the variation in the

�13C is explained by time. Beginning at ca. calA.D. 700 there is a bifurcation in values betweenenriched and depleted. Limiting the values to be-tween 300 B.C. and A.D. 700 results in a strongercorrelation (r = .574, p < .05). While this trendsuggests increased maize C contribution toresidue formation, microbotanical analyses wouldhelp to determine if maize was in use during thisinterval. After A.D. 700 there is a nonsignificant,weak negative correlation between �13C and dates(r = –.183, p > .05). The variation in �13C valuesafter cal A.D. 900 may reflect vessel assemblagesat sites representing larger, more sedentary pop-ulations that include morphologically similar ves-sels used to cook different C3 resources and/ordifferent forms of maize, such as flour/meal (en-riched) as opposed to whole kernel (depleted[Hart et al. 2009:2211]), and/or to facilitate dif-ferent modes of cooking (Rice 1987; Skibo 1992).

rePOrtS 321

Figure 2. Bulk �13C values on charred, encrusted cooking residues from the Grand River and Saginaw River basins,Michigan, plotted against calibrated median probabilities of direct accelerator mass spectrometry dates on the sameresidues, with locally weighted scatter plot smoothing (solid line), distance-weighted least squares (dashed line), and lin-ear smoothing (dotted line). The horizontal line represents the –24‰ threshold suggested by Morton and Schwarcz(2004) for the presence of maize in bulk �13C values.

AQ77(2)8-Hart_Layout 1 4/10/12 3:30 PM Page 321

Conclusions

Because taphonomic processes make the recoveryof maize macrobotanical remains from early con-texts in ENA unlikely, archaeologists must pursue

other lines of evidence for regional maize histo-ries. One line of evidence with a varied historyhas been bulk �13C values on residues, which areregularly reported by AMS laboratories and aretherefore readily available. Experiments have

322 american antiquity [Vol. 77, no. 2, 2012]

Table 3. Data from Southwestern Wisconsin and Northeastern Illinois Sites.

Site State Lab # �13C 14C B.P. Cal. 2� (median prob.)

Macktown IL ISGS A1209 -29.6 2255±20 393 (284) 210 B.C.Richter WI Beta 215681 -25.8 2100±40 346 (124) 2 B.C.Sloan Site WI ISGS A1098 -27.2 1990±20 41 B.C. (A,D. 12) 59Outlet Site WI ISGS A1237 -24.5 1920±20 28 (83) 129Sloan Site WI ISGS A1094 -25.8 1895±20 56 (104) 209Sloan Site WI ISGS A1099 -24.5 1890±20 63 (106) 210Peterson Site WI UGAM 2721 -29.0 1840±40 75 (174) 313Peterson Site WI UGAM 2720 -27.9 1800±20 92 (216) 339Sloan Site WI ISGS A1097 -25.8 1710±20 256 (337) 399Lange/Pottery Site WI UGAM 2728 -25.5 1610±50 267 (459) 566Aztalan WI UGAM 2726 -25.2 1500±50 433 (563) 645Aztalan WI UGAM 2725 -25.8 1380±50 568 (650) 769Kautz IL ISGS A1100 -24.5 1360±20 644 (660) 680Aztalan WI UGAM 2723 -23.6 1340±40 635 (678) 774Koshonong Mound Group WI ISGS A1200 -25.4 1275±20 675 (723) 775Aztalan WI UGAM 2738 -22.0 1260±40 668 (744) 870Aztalan WI UGAM 2727 -18.1 1250±40 674 (755) 874Aztalan WI ISGS A1251 -23.5 1230±20 694 (788) 874Aztalan WI ISGS A1106 -20.1 1120±20 888 (936) 980Pipe Site WI ISGS A1104 -25.4 1025±20 984 (1007) 1029Washington Irving IL ISGS A1081 -25.8 1005±20 987 (1020) 1119Aztalan WI ISGS A1105 -19.5 980±20 1015 (1041) 1154Carcajou Point WI UGAM 2718 -24.2 970±60 973 (1085) 121390T-265 WI UGAM 2740 -25.5 970±30 1016 (1091) 1155Carcajou Point Locality WI ISGS A1114 -25.9 915±20 1035 (1095) 1171Aztalan WI UGAM 2724 -26.3 920±40 1026 (1107) 1208Crescent Bay Hunt Club WI UGAM 2731 -17.5 920±40 1026 (1107) 1208Aztalan WI UGAM 2739 -24.9 910±40 1031 (1115) 121147LI103 WI ISGS A1089 -25.0 900±20 1042 (1123) 1210Crescent Bay Hunt Club WI UGAM 2729 -22.0 880±40 1035 (1157) 1225Pipe Site WI ISGS A1074 -26.3 880±20 1048 (1171) 1218Washington Irving IL ISGS A1080 -24.7 880±20 1048 (1171) 1218Pipe Site WI ISGS A1075 -25.3 830±20 1169 (1217) 1259Crescent Bay Hunt Club WI UGAM 2732 -21.9 800±40 1165 (1234) 1279Pipe Site WI ISGS A1078 -24.2 790±20 1217 (1244) 1271Crescent Bay Hunt Club WI Beta 180695 -25.3 750±40 1210 (1262) 1380Crescent Bay Hunt Club WI ISGS A1653 -21.8 795±15 1218 (1242) 1265Crescent Bay Hunt Club WI ISGS A1654 -19.8 765±15 1227 (1263) 1277Crescent Bay Hunt Club WI UGAM 2730 -23.6 730±40 1217 (1273) 1385Schlage Site WI ISGS A1477 -23.1 735±20 1254 (1274) 1292Crescent Bay Hunt Club WI ISGS A1070 -21.5 700±20 1269 (1285) 1380Fisher Site IL ISGS A1082 -25.5 675±20 1276 (1297) 1387Nitschke WI ISGS A1095 -21.6 550±15 1324 (1404) 1424New Lenox Site IL ISGS A1192 -23.8 415±20 1436 (1457) 1609Horton Site IL ISGS A1102 -25.6 380±25 1446 (1495) 1630New Lenox Site IL ISGS A1189 -20.8 365±20 1452 (1511) 1631New Lenox Site IL ISGS A1187 -24.1 330±25 1482 (1564) 1642JAAP (Joliet Arsenal) IL ISGS A1208 -24.1 285±20 1521 (1565) 1658Zimmerman IL ISGS A1085 -25.3 230±20 1643 (1667) 1954

AQ77(2)8-Hart_Layout 1 4/10/12 3:30 PM Page 322

shown that the relationships between bulk �13Cvalues from residues and maize use are complex.It is not possible to determine the percentage ofmaize cooked in a pot relative to C3-pathwayplants or consumers or even to determine if maizewas cooked in a pot using a threshold �13C value.

However, it is possible that bulk �13C valueson large regional series of directly AMS-datedresidues may indicate trends that reflect maizeuse history. Here we have examined trends inbulk �13C values for 57 directly dated residuesfrom central New York. That maize contributedto the formation of at least some of the residuesis known because phytolith assemblages extractedfrom 18 of the residues originated from maize.The results of our regional analyses show strongtrends for enriched bulk �13C values and, there-fore, maize C contribution to residue formationthrough time in two of three regions. We cannot

specify whether the increased contribution re-sulted from higher proportions of maize beingcooked in a given pot and/or changes in the formof maize being cooked, such as maize meal orflour as opposed to whole kernels. However, theresults do suggest the potential value of chrono-logical studies of bulk �13C values from directlydated residues as a complement to other lines ofevidence for maize use histories. Moreover, theseresults reveal the necessary regional data require-ments for effective application of the procedurein tandem with other lines of evidence.

Analyses of large data sets of bulk �13C valuesfrom directly dated residues from the Saginawand Grand River basins of Michigan and the south-western Lake Michigan region further indicate thelimitations of bulk �13C values even in large series.The Saginaw River Basin now has microbotanicalevidence for maize dating from cal 2� 350–40

rePOrtS 323

Figure 3. Bulk �13C values on charred, encrusted cooking residues from the southwestern Lake Michigan region, plottedagainst calibrated median probabilities of direct accelerator mass spectrometry dates on the same residues, with locallyweighted scatter plot smoothing (solid line), distance-weighted least squares (dashed line), and linear smoothing (dottedline). The horizontal line represents the –24‰ threshold suggested by Morton and Schwarcz (2004) for the presence ofmaize in bulk �13C values.

AQ77(2)8-Hart_Layout 1 4/10/12 3:30 PM Page 323

B.C. to cal 2� A.D. 1440–1640 (Raviele 2010).However, the available �13C data compiled fromvarious independent projects producing AMSdates on residues do not show statistically signif-icant trends. A lack of chronologically continuousdata points to the need for additional assays onresidues from data-deficient time periods.

The direct AMS-dated southwestern LakeMichigan region residues do provide continuouschronological data, although somewhat weightedtoward the later half of the sequence. A lack ofmicrobotanical information, however, poses a dif-ferent problem than the Michigan sample andpoints to the need for equivalent and comparableinformation sets across regions of ENA. The dataevince more enriched �13C values through time,specifically in the time interval before ca. calA.D. 700. The correlation between �13C valuesand dates is not as strong as the correlations fromNew York. Particularly evident is a bifurcation in�13C after ca. cal A.D. 700. This contrasts withthe New York data, which evince a steady en-richment of values. These different results mayreflect regional differences in food preparationand/or use of pottery.

The bulk �13C values at any given time in thesequence from each of these regions indicate thedifficulty in interpreting bulk �13C values. Thevariation may reflect different C3 resource mixeswith maize, and/or different forms of maize beingcooked, and/or different proportions of resourcesbeing mixed with maize, or the absence of maize.However, the overall trend in bulk �13C valuesfor the sequence for New York cannot be ex-plained in the absence of maize and is supportedby phytolith evidence for maize use through thesequence. The current analysis suggests that largeseries of bulk �13C values on directly AMS-datedresidues may be of value as one line of comple-mentary evidence to elucidate maize use historiesin other areas of ENA. Our results emphasize theneed for systematic sampling and microbotanicalanalyses in order for bulk �13C values to be in-formative. Of particular note is that not all sam-ples are large enough to produce bulk �13C data.The 49 assays reported here for the southwesternLake Michigan region, representing less than halfof those submitted for AMS dating, were the onlyones large enough to assay for �13C.

Acknowledgments. The New York assays were funded by theNew York State Biodiversity Research Institute, the New YorkState Museum, and the University at Albany–State Universityof New York. The �13C values for the Michigan acceleratormass spectrometry dates series were compiled through thegenerosity of several colleagues and their institutions, includ-ing Scott Beld (University of Michigan), Janet Brashler (GrandValley State University), Sean Dunham and Michael Ham-bacher (CCRG, Inc.), Barbara Mead (Michigan Office of theState Archaeologist), Maria Raviele (Glenn A. Black Labo-ratory of Archaeology), and Jeffrey Sommer (Saginaw Ar-chaeological Commission). The data from Illinois and Wis-consin include samples donated by William Green (BeloitCollege), Rochelle Lurie (Midwest Archaeological ResearchServices, Inc.), Danielle Benden (University of Wisconsin,Madison), and James Brown (Northwestern University). Theabstract was translated into Spanish by Laura P. Villamil. Fi-nally, thanks go to the anonymous reviewers of AmericanAntiquity and to Dr. Roberts for their insights.

References Cited

Beld, Scott G. 1993 Site 20IA37 (Arthurburg Hill Earthworks), Lyons

Township, Ionia County, Michigan. In Lyons TownshipArchaeological Survey, S-92-313, edited by S. G. Beld,pp. 3–82. Archaeological Survey Completion Report sub-mitted to the Michigan Office of the State Archaeologist,Alma College, Alma, Michigan. Report on file at theOffice of the State Archaeologists, Michigan Departmentof History, Arts and Libraries, Lansing, Michigan.

Boyd, Matthew, and Clarence Surette 2010 Northernmost Precontact Maize in North America.

American Antiquity 75:117–133.Branstner, Mark G., and Michael J. Hambacher 1995 1991 Great Lakes Gas Transmission Limited Part-

nership pipeline expansion projects: Phase III investigationsat the Cassasa [i.e. Casassa] site (20SA1021), SaginawCounty, Michigan. Report No. 95-01. Report submittedto the Federal Energy Regulatory Commission and theMichigan State Historic Preservation Officer. Great LakesResearch Associates, Inc., Williamston, Michigan.

Brashler, Janet G., Michael J. Hambacher, Terrance J. Martin,Katherine E. Parker, and James A. Robertson

2006 Middle Woodland Occupation in the Grand RiverBasin of Michigan. In Recreating Hopewell, edited byDouglas K. Charles and Jane E. Buikstra, pp. 261–284.University Press of Florida, Gainesville.

Harrison, Roman G., and M. Anne Katzenberg 2003 Paleodiet Studies Using Stable Carbon Isotopes from

Bone Apatite and Collagen: Examples from SouthernOntario and San Nicolas Island, California. Journal ofArchaeological Science 22:227–244.

Hart, John P. 1999 Maize Agriculture Evolution in the Eastern Woodlands

of North America: A Darwinian Perspective. Journal ofArchaeological Method and Theory 6:137–180.

2008 Evolving the Three Sisters: The Changing Historiesof Maize, Bean, and Squash in New York and the GreaterNortheast. In Current Northeast Paleoethnobotany II,edited by John P. Hart, pp. 87–99. New York State MuseumBulletin 512. University of the State of New York, Albany.

324 american antiquity [Vol. 77, no. 2, 2012]

AQ77(2)8-Hart_Layout 1 4/10/12 3:30 PM Page 324

Hart, John P. (editor) 2008 Current Northeast Paleoethnobotany II. New York

State Museum Bulletin 512. University of the State ofNew York, Albany.

Hart, John P., Betty Jo Brumbach, and Robert Lusteck 2007a Extending the Phytolith Evidence for Early Maize

(Zea mays ssp. mays) and Squash (Cucurbita sp.) inCentral New York. American Antiquity 72:563–583.

Hart, John P., William A. Lovis, Janet K. Schulenberg, andGerald R. Urquhart

2007b Paleodietary Implications from Stable Carbon IsotopeAnalysis of Experimental Cooking Residues. Journal ofArchaeological Science 34:804–813.

Hart, John P., and R. G. Matson 2009 The Use of Multiple Discriminant Analysis in Clas-

sifying Prehistoric Phytolith Assemblages Recovered fromCooking Residues. Journal of Archaeological Science36:74–83.

Hart, John P., Robert G. Thompson, and Betty Jo Brumbach 2003 Phytolith Evidence for Early Maize (Zea mays) in

the Northern Finger Lakes Region of New York. AmericanAntiquity 68:619–640.

Hart, John P., Gerald R. Urquhart, Robert S. Feranec, andWilliam A. Lovis

2009 Nonlinear Relationship Between Bulk �13C andPercent Maize in Carbonized Cooking Residues and thePotential of False Negatives in Detecting Maize. Journalof Archaeological Science 36:2206–2212.

Hastorf, Christine A., and Michael J. DeNiro 1985 Reconstruction of Prehistoric Plant Production and

Cooking Practices by a New Isotope Method. Nature315:489–491.

Jeske, Robert J., and John D. Richards 2010 A New and Improved Wisconsin Woodland Chronology

from Wisconsin: Dates from Organic Residues on CeramicVessels. Paper presented at the 75th Annual Meeting of theSociety for American Archaeology, St. Louis, Missouri.

Lovis, William A. 1990 Curatorial Considerations for Systematic Research

Collections: AMS Dating of a Curated Ceramic Assemblage.American Antiquity 55:382–387.

Messner, Timothy C., Ruth Dickau, and Jeff Harbison 2008 Starch Grain Analysis: Methodology and Applications

in the Northeast. In Current Northeast PaleoethnobotanyII, edited by John P. Hart, pp. 111–127. New York StateMuseum Bulletin 512. University of the State of NewYork, Albany.

Morton, June D., and Henry P. Schwarcz 2004 Paleodietary Implications from Stable Isotopic Analysis

of Residues on Prehistoric Ontario Ceramics. Journal ofArchaeological Science 31:503–517.

Parker, Kathryn E. 1996 Three Corn Kernels and a Hill of Beans: The Evidence

for Prehistoric Horticulture in Michigan. In Investigatingthe Archeological Record of the Great Lakes State: Essaysin Honor of Elizabeth Baldwin Garland, edited by MargaretB. Holman, Janet G. Brashler, and Kathryn E. Parker, pp.307–339. New Issues Press, Kalamazoo.

Raviele, Maria E. 2010 Assessing Carbonized Archaeological Cooking

Residues: Evaluation of Maize Phytolith Taphonomy andDensity Through Experimental Residue Analysis. Un-published Ph.D. dissertation, Department of Anthropology,Michigan State University, East Lansing.

Rice, Prudence M. 1987 Pottery Analysis: A Sourcebook. University of Chicago

Press, Chicago.Rose, Fionnuala 2008 Intra-Community Variation in Diet During the Adoption

of a New Staple Crop in the Eastern Woodlands. AmericanAntiquity 73:413–439.

Seinfeld, Daniel, Christopher van Nagy, and Mary D. Pohl 2009 Determining Olmec Maize Use Through Bulk Stable

Carbon Isotope Analysis. Journal of ArchaeologicalScience 31:2560–2565.

Skibo, James M. 1992 Pottery Function: A Use-Alteration Perspective.

Plenum Press, New York.Sommer, Jeffrey D. 2003 A Middle Woodland AMS Date from Saginaw County,

Michigan. The MichiganArchaeologist 49(3-4):87–95.Staller, John E., Robert H. Tykot, and Bruce F. Benx (editors) 2006 Histories of Maize: Multidisciplinary Approaches to

the Prehistory, Linguistics, Biogeography, Domestication,and Evolution of Maize. Academic Press, Burlington,Massachusetts.

Notes

1. Raviele’s (2010) experimental evidence indicates that phy-toliths will not occur in every residue containing maize C. There-fore, we cannot assume that the absence of maize phytoliths in aresidue indicates that maize was not cooked in the pot.

2. AMS dates and bulk �13C values are not available formost of the residues from which microbotanical evidence wasobtained by Raviele (2010).

rePOrtS 325

AQ77(2)8-Hart_Layout 1 4/10/12 3:30 PM Page 325